Combination beam plate and outer shield



Jan. 14, 1958 c.'M. MORRIS 2,820,169

COMBINATION BEAM PLATE AND OUTER SHIELD Filed' March 14, 1955 United states Patent U COMBINATION BEAM PLATE AND OUTER SHIELD Clifford M. Morris; Hackensack, NJ Jr, assignor to Radio Corporationof America; acorporation of Delaware Application March 14, 1955, Serial-No. 494,111 14 Claims. (Cl; 3'13*'299) This invention: relates to' electron" tubes, andmore" especially it relates to novel electrode structures and arrangements for such tubes.

A- principal object of the invention is to provide-a novelcomposite electrode and'shield for elect-ron tubes:

wherein electrostatic shielding between certain electrodes A further' object is to provide a nove'lelectrode con-"- figuration and arrangement which is especially useful in so-called pentode or beam powertubes.

A feature of the invention relatesto an improved electrode' which can be' economicallymanufactured from' sheet metal so as to form a compositebeam-defining and secondary electron suppressor electrode.

Another feature relates to a novel beam'plate'or. suppressor electrode for pentodes and beam power-tubes of the dual interconnected anode kind, which plat'e -or electrode can be readily assembled around-a respective: anode-forshieldingmit completely except at the region where it is to receive electrons fromv an. associated: cathode. Asa result ofthis feature,- it is: possible-to manufacture such a mount with electrostatically shieldedl anodes while leaving the region intervening between .the anodes and occupied by one or more grids; open to visual inspection.

Another feature relates to a novel compositeshield ing and beam definingiplate for electronmbeswhich enables small tubes such as so-called miniature tubes-'to be assembled andreadilyinspected during assembly: for grid alignment, pushed grid turns, and the like.

A -still further feature relates to the novel -organiza-' tion, arrangement, and relative'configuration and-location of parts which cooperately constitutean improvedpentode or beam power tube.

Other features andadvantages will appear as' the ensuing specification proceeds.

Inthe drawing,- which shows typical --exemplifica'tions;

Fig. l is an elevational view of an electron tube accord-'- ing to the invention;

Fig. 2- is a sectional view' of -Fig; 1" taken along' the line- 2-2 thereof and viewed-in: the dire'ction of the arrows;

Figi 3- is =an enlarged erspective view of -one of-the composite electrodesof Fig; 1;-

Fig. 4 is a sectional view of Fig. 1 take'ti albng the line 4-4 thereof: and viewed 1 in the' direction ofthe arrows;

Fig. 5 is a sectional view of Fig. 1 taken along the line 5-5 thereof and' vi'ewed in the -di-rectiomofthe arrows;

Fig. 6 is a schematic plan view ofF-i'gi; lushowinguthe manner ofrinterconnectingsthe-various electrodes with the contact pins of thetube;

Fig.-i 7 is a-:perspective-viewohm-modification otlthe composite electrode of Fig. 3;

Z,82@,l69 Raterrted Jaln. 14, v 1958 2 Fig; 8' is ap'erspective vi'ew ofanother modification: of the composite electrodeof- Fig. Referrin-"gto Fig. 1, there is sho'wn anyweltlcnowd form of enclosing bulb or envelope 10 0fglassor other suitable material closed oifat its lower end' by a button In the particular tube shown in the drawing,-vthe=-cat hodey 21 comprises a heatable filament 3 coated on exterior surface with any" wellknown kind" of i electron emissive materiaL- The filament-is connected to-"a metal pin 23 centrally sealed in the header 11 and'eleetrically: con=- nectedto another pin 16'." The-centralpin 23-does not extend externally of the header 11. Theu'pperendof the filamenbzz istanchored tea-metal tab 24 to maintain: the filament: under suitabletension.

Surrounding; the cathode-are two-grid electrodes 25; 26;: These gridsmay be of anyv-well knownconstru'ction; for exampfleeachmay: be in the form of a: fin'ewire helically" woundaround a pair ofspaced paralleb ups rights-or grid side rods 27, .28; and 29'; 30(see Fig. 2:). Thesesiderods are omitted from-Pig. LfOr thepurpQse of clarityfin the drawing. While -thedrawingashows gnids 25 and 26 as of elliptical contour in plan view,- this' contour maybe circular or other desired shape? The gridturns extending between -the--resp ective side rods to' which they areanchored are known as grid lateralsn Preferably the grids are wound and L supported-- so-* that the lateralsof the two"=grids "are inalignment.

Located on t oppositesides of'- the-' two grids are twoanodes 31, 32,- eaclr for example: in the form of" i a flatmetal strip these anodes being loc'ated in symmetrical alignment withleach other andwith tlie cathcude'Z-I'l Each of the anodes is-enclosed: or surrounded byra composite beam-defining and". secondary electron suppressor plate 33, .34: One of these plates, namelyr plate 3fi'for 'the" anode 31 is shown in enlarged perspect-ive form in -Fig::- 3*. Each of these" plates is formedirom a flat metal-strip, the-end sections 35, 36 ofwhich 't arebent-back towards each other to form a substantially:semiwylindrical tubular unit; The -flat front face'37 of' this unitis provided :with an elongated window- 38 centrallyw'theieofi 'and'docated in alignmentwith the correspondinganod 31.2 The: fiat central'porti'on 37 is-also provided at 'opfposite ends-With integral wings 39, 40 for purposes to be-' descr i=beda'== If desired the bent back wing portions 35 and-36' can be welded-or otherwise united at'theinabutting'sedgesr The wings 39, 40'extend substantially b6YOI1d"th8IldS-*Ol all the electrodes and-thus serve as end shields for ele'ct rd statically shielding the ends-of the anodes'tromtlie'ig'rids and cathode:

As shown-- in Fig: 1, the vari'ous electrodes are as sembled'as a unitar-y mount between a pai-r of insulat'or spacerdiscs: such as the bottom mica" disc 41- and the top mica disc 42. Each of these inicas -has a central opjening ithroughwhich pass-the corresponding ends of the cat hode 2L- Thesemicas also have -respective'fopen ings :toreceive the ends of the grid side-*-rods "2 7 =30', whichbyi anywell known means can be anchored against connected by a U-shaped metal strap?45;f "Welded or otherwiseiastened to the projectingrwings-illl; and 43' and bearing against the mica 42 is a channel-shaped metal 3 strip 46 -(see Fig.4) which has at one end a struck-up portion which forms the filament anchoring lug 24 hereinabove mentioned. A fine wire filament tensioning spring 47 is welded to the lug 24 and to the upper end of filament 21. The opposite side of member 46 has a downwardly struck tab which fits into a corresponding downwardly between the anode lead-in member and thej en grid lead-in member to complete the shielding therebetween.

A suitable getter unit 51 may be attached to the upper member 46 so that when the gettering material is flashed the deposit is confined to the upper end of the interior surface of bulb 10.

The manner of connecting the various electrodes to the respective lead-ins or pins 1219 is schematically illustrated in Fig. 6. When the tube is to be used as a pentode, the first grid 25 acts as a control grid and the second grid acts as a shield grid. The electrodes 33 and 34 act as complete electrostatic shields for shielding the respective anodes from the associated grids and also they serve as collector electrodes for secondary electrons which may be emitted from the respective anodes. Furthermore, the windows 38 and 52in these composite shielding and suppressor electrodes act in the nature of beam-defining windows.

From the foregoing it will be seen that the anodes are substantially completely shielded from the associated grids without the necessity of employing an external shield which ordinarily surrounds the interelectrode space. As will be seen from Fig. 1 of the drawing, the finally assembled mount is completely open to inspection in the space between the electrodes 33 and 34, thus enabling the alignment of the grids to be readily observedand adjusted if necessary. Furthermore, by combining the outer shield and beam plate as a single element, the cost of manufacture and assembly of the tube can be reduced while permitting pentode tubes of small or miniature size to be manufactured economically.

If desired, the windows 38 and 52 in each of the composite beam plate and shielding electrodes can be formed with integral wings so as further to define the electron beam reaching the respective anode. Such a modification is shown in Fig. 7, wherein the parts corresponding to those of Fig. 3 carry the same designation numerals. As will be seen in Fig. 7, the member 33 is formed with integral diverging strips or wings 53, 54 along the edges of the window 38. While Fig. 7 shows these wings diverging outwardly in a direction facing the cathode, it will be understood that they may be located interiorly of the member 33 facing the respective anode.

1 The invention is not limited to any particular number or arrangement of the beam-defining windows 38. For example, as shown in Fig. 8, the composite electrode 33, instead of being formed with a single longitudinally extending window, may be provided with a series of laterally extending windows 55.

' While the invention has been described particularly in connection with a so-called pentode tube, it will be understood that the composite beam-defining and shielding electrode, such as shown in Figs. 3, 7, and 8, may be used in other types of electron tubes. Similarly, while the tube has been shown as embodying a so-called filamentary cathode, it will be understood that this cathode may be of the so-called indirectly heated type, including a cathode sleeve with an internal heater element or filament.

- What is claimed is: i

1. An electron tube comprising, cathode means to develop an electron stream to be controlled, an anodeupon which the electron stream terminates, and a composite electrostatic shielding and electron stream-passing electrode within said tube, said electrode substantially surrounding said anode but having a beam-passing aperture facingthe cathode means.

2. An electron tube comprising a cathode to develop an electron stream to be controlled, a pair of discrete anodes disposedon opposite sides of and in a plane including said cathode, and discrete electrostatic shielding electrodes each individually electrostatically isolating a,

corresponding anode except for a portion of the wall thereof which is provided with a window on the side facing the cathode to permit the electron stream to pass from the cathode tothe anode. 4

3. An electron tube'comprisin'g" acathode to develop an electron stream to be controlled, a pair of discrete anodes disposed on opposite sides of and in a plane including said cathode, at least one control grid located. between said cathode and anodes, and a pair of discrete composite shielding and secondary emission collector electrodes each individually electrostatically isolating a corresponding anode from said grid except for a beam-- passing window therein through which the electron streami passes from the cathode to the anode.

4. An electron tube comprising an elongated cathode to develop electron beams extending therefrom in opposite directions, at least one control grid surrounding said cathode, a pair of discrete anodes located on opposite sides of said control grid in alignment with said cathode, and a pair of shielding plates each substantially enclosing only' a corresponding one of said anodes, said shielding plates each having a beam-passing window facing said cathode.

5. An electron tube according to claim 4, in which each: of said shielding plates has a longitudinal window having its length substantially parallel to the length of the cathode.

6. An electron tube according to claim 4, in which each of said shielding plates has a pair of diverging wings at the edges of the beam-passing window therein.

7. An electron tube according to claim 4, in which each of; said shielding plates has a plurality of beam-passing windows extending transversely to the length of the cathode.

8. An electron tube according to claim 4, in which each of said shielding plates has at its opposite ends wings for shielding the respective ends of the anodes from the corresponding ends of the grid.

9. An electron tube mount comprising a pair of insulator spacers between which a plurality of electrodes are mounted, said plurality of electrodes including a central elongated cathode, a pair of grids surrounding the cathode, said grids having respective side rods located in substantially the same plane with said cathode, a pair of discrete anodes located on opposite sides of the cathode, and a pair of discrete and approximately tubular electrostatic shielding plates each surrounding a respective one of the anodes alone, each of said tubular plates having at least one beam-defining window therein for the electrons passing between the cathode and anode.

10. In combination, a composite anode-shielding and beam-defining electrode for electron tubes, comprising a sheet metal element of substantially tubular shape and having at least one elongated beam-defining window therein, and an anode within said electrode,,said window providing communication to said anode from the exterior of said electrode.

11'. A composite electrode according to claim 10 in which the beam-defining window extends along the length of the electrode.

12. A composite electrode according to claim 10 in which said element is formed with integral shielding wings extending therefrom.

13. A composite anode-shielding and beam-defining electrode for electron tubes, comprising a sheet metal element "of substantially tubular shape and having a plurality of beam-defining windows extending transversely to the length of said electrodes.

14. In combination, a flat anode, a cathode and a tubular electrostatic shielding and beam forming member surrounding said anode, and having a flat portion extending between said cathode and anode, and in a plane parallel to said anode, said flat portion having a window therein to provide a straight line electron communication between said anode and cathode in a direction normal to said anode.

References Cited in the file of this patent UNITED STATES PATENTS Ruben Oct. 27, 1925 Mulder Oct. 18, 1932 Orth Mar. 19, 1935 Machlett .j. Oct. 4, 1938 Bowie ..e Sept. 5, 1939 Hergenrother July 9, 1940 Varelo Apr. 29, 1941 Burnside Oct. 30, 1951 FOREIGN PATENTS France June 19. 1939 

